Manufacture of soap



Nov. 19, 1946. 1.. SENDER MANUFACTURE OF SOAP Filed Nov. 25, 1943 N MN M MW QYADMERQWU UNITED STATES PATENT OFFICE.

MANUFACTURE OF SOAP Leopold Sender, Baltimore, Md., assignor-to The Sharples Corporation, Philadelphia, Pa., a corporation of Delaware Application November 25, 1943, Serial No. 511,706

1 Claim. (Cl. 260-418) The present invention relates to the art of soap making, and was conceived as a method of making soap continuously with the aid of centrifugal separators.

posed between these two mixing steps. In the practice of the present invention, the fat and reagent are first mixed during maintenance of a saponifying temperature to cause saponiflcation,

Processes for the manufacture of soap by pass- 5 and the soap formed asa result of the reaction ing a saponifying reagent continuously into conis grained. The resulting mixture is then subfiuence with a source of fat, saponifying the fat jected to agin y maintenance of a period Of by passage of the mixture at saponifying temrelative quiescence or lesser degree of agitation, perature continuously through mixing apparatus, and a part of the aqueous phase settles from and separating spent reagent from soap by centhe grained soap during this aging step and is trifugation are described and claimed in the paremoved. The mixture of grained 0 p and Spent tents of Ashton T. Scott, 2,300,749 and 2,300,750, saponifying reagent remaining after removal of of November 3, 1942. The present invention is a portion of said saponifying reagent is then prefprimarily a development and improvement with erably subjected to a further period of agitation respect to the procedure of these two patents. in order to provide sufiicient dispersion of the In the processes of the above-mentioned Scott soap in the aqueous phase to afford substantially patents, the fat is continuously saponifled by uniform distribution of the soap in that phase as treatment with a saponifying reagent such as lye, the mixture is passed to the centrifugal separathe saponification being accomplished by intensetor for separation of the remaining spent reagent ly mixing the fat and lye while passing them from the grained soap. at a saponifying temperature through mixing ap- The succession of steps of the invention, as deparatus. The resulting soap-containing mass is scribed above, may be performed both in the first maintained under intensive agitation until it is stage of soap making as described in connection passed into a centrifugal separator for removwith the first stages of the respe v D e P ing the spent aqueous reagent from th soap, ents to Scott discussed above, and in any or all The soap is grained, and thus conditioned for of the series of subsequent saponifying stages, of removal of the spent aqueous reagent, prior to which each involves addition of saponify centrifugation, by the addition of a salt solution, n rainin nd p rati n as described in or an excess of saponifying reagent which serves the prior Scott patents. Each stage in which a as a salting-out agent. In the process of Patsaponifying reagent is added is thus referred to cut 2,300,750, the salting-out operation is accomas a saponifying stage herein, even though the plished by addition of the salting-out agent beaddition of saponifying reagent in the last such fore the start of the saponification reaction. stage may be wholly or partly for the purposes The present invention may include any or all of recovering glycerine d P p ti o fi of the features of either of the prior patents to ishing, and no actual saponification occurs in Scott discussed above. It includes steps of efiectsuch stage. ing continuous saponification by passage of the y the Practice f the invention s disc s ed fat and saponifying reagent together through a above, the following advantages are attained. saponifying mixer, graining the mixture by addi- The quiescent treatment or churning obtained tion of a salting-out agent either simultaneously in the aging step causes a change in the mixwith the saponifying reagent or subsequently to ture which facilitates subsequent centrifugation. the addition thereof, and centrifugation of the The removal of a part of the aqueous phase durmixture of spent saponifying reagent and grained ing this aging step also improves centrifugation, soap resulting from the saponification while the and makes it possible to improve the throughgrained soap is in a condition of substantially put of the centrifugal in separated soap or to uniform dispersion in the spent saponifying reimprove the degree of removal of aqueous phase agent, from the soap product. It has been found that,

The novel feature of the present invention conin cases in which the saponified and grained mixsists in the fact that the mixing step by which ture presents substantial diificulty of separation intimate contact of the saponifying reagent with 60 in the practice of the Scott patents, the incluthe fat is attained to cause the saponification and to bring the soap formed by the saponifying reaction into a state of uniform dispersion is divided into two steps, and a step of aging and sepsion of the intervening aging step in accordance with the present invention assists in avoidance of these difliculties.

The aging treatment also provides a longer oration of a part of the aqueous phase is intertime of contact between the fat and lye, or the formed soap and lye, and this longer period of contact with the saponifying reagent tends to destroy constituents of the mixture which would otherwise cause rancidity of the soap after the soap-making operation has been completed.

In addition to the above advantages, the aging treatment, by giving a longer time of contact of the unsaponified fat with the lye, assists in solution of lye and salt, designed to effect saponification of the fat and graining of the soap formed by the saponifying reaction, as described in Scott Patent 2,300,750. As illustrated in the fiow sheet, the solution of lye and brine employed in the first stage of saponification may be a solution derived in whole or in part from the step of separation of a subsequent stage; i. e., the

process may involve counter-current operation as described in the prior Scott patents. The fat from container l0 and saponifying reagent from container I I may be pumped into confluence with each other by pumps I2 and [3 to and through the mixer M in the desired ratio. The reaction mixture, or its constituents, is (are) heated to.a temperature (e. g 200 F.) sufliciently high to effect saponification of most of the fat during passage through the mixer Hi. The mixture is maintained in a state of intensive agitation during passage through the mixer l4 in order to insure rapid saponification of the fat. When a graining agent such as salt is included with the saponifying reagent, the soap is grained promptly upon formation thereof. It is possible, however, to introduce the saponifying reagent and graining agent separately, as described in Scott Patent 2,300,749, and when operation of this type is accomplished, the graining agent is preferably added before the reaction mixture leaves the mixer i l, or at least before it enters the ager i5.

The reaction mixture is passed continuously from mixer it through an aging tank 55. The

mixer id is preferably provided with agitating blades to insure violent agitation, but the ager i5 need not be provided with such elements. It is desirable that the mixture be gently agitated during passage through the ager I5, but this result can be accomplished either by the natural movement of the mixture through that tank, or by provision of agitating blades which provide much less violenc than that maintained in the mixer l4.

The ager i5 is preferably provided with a tapered bottom designed to permit removalof spent aqueous reagent separated from the grained soap during the aging step through the draw-off valve l1. Thus, the ensuing s -p of centrifugation is facilitated by removal at this point of a part of the aqueous phase which would otherwise be removed by subsequent centrifugation.

As the result of maintenance of relative quiescence during passage of the mixture through the ager I5, aqueousphase which still remains dispersed in grained soap flowing from that ager will be much less nearly uniformly distributed than would be the case if the mixture from mixer I were to be introduced directly from that mixer into centrifugal 18. This may cause dimculty in subsequent centrifugation unless corrected. In order to attain a degree of uniformity of mixing of aqueous phas and grained soap flowing from ager I5 sufficient to insure efflcient centrifugation, the grained soap-containing mixture flowing from ager I5 is passed through a mixer l6 which provides a higher degree of agitation than ager l5 and effects uniform dispersion of the soap in the remaining aqueous phase before the material enters the centrifugal.

From the' mixer l6 the mixture of spent reagent and grained soap is passed to centrifugal I 8 for separation of the spent reagent from the soap as in the two Scott patents referred to above.

After discharge from the centrifugal 18, the 'largely saponified mass containing the soap formed in the first stage is subjected to a second stage of saponification in order to complete conversion of the source of fat into soap. As in the prior Scott patents, this may be accomplished by introduction of the saponifying reagent into the cover of centrifugal l8. Thus, a solution of lye and brine, whichmay either be a fresh solution or a solution derived from a subsequent stage of treatment, is introduced from container [9 into the cover of centrifugal I8 by pump 20, and the resulting mixture is passed thence by pump 2| to mixer 22, through this mixer 22 to ager 23 and from ager 23 through mixer 24 to centrifugal 25, these elements of the flow sheet accomplishing the same functions as are performed by the pumps and elements 14, i5, i6 and. N3 of the first stage of the process, as described above. 7

The soap discharged from the second stage centrifugal 25 may be subjected to further treatment, as described in the two Scott patents referred to above, and if such further treatment includes further steps of saponification, they will preferably include an aging step, as described above with respect to the first two stages of treatment. The performance of the step of aging has a particular advantage in the last stage of soap making, since the maintenance of the fully saponified soap-containing mixtur in contact with an excess of the free alkali for a substantial period of time assists in avoiding rancidity, as discussed above, and it is therefore desirable to provide an a ing period after the fat has been fully saponified.

The partly spent aqueous solution discharged from the centrifugal 25 may be passed by pump 21 to container II for reuse in the first stage of the process, in order to make the process truly counter-current, as described in the Scott patents referred to above. Aqueous reagent withdrawn from ager 23 through valve 26 may be combined with the partially spent aqueous reagent from centrifugal 25 for recycling to the earlier stage of the process therewith.

Spent aqueous reagent removed through valve I! from ager l5 may similarly be combined with aqueous phas discharged from centrifugal l8, in order that the combined aqueous phase thus obtained may be subjected to treatment for glycerine recovery.

Various modifications in the above-described procedure are available to the person skilled in the art, anr are hence within the scope of the invention. For example, instead of including the 5 graining reagent 'as apart of the saponifying solution, this graining reagent may be added subsequently to the saponifying reagent, as described in Scott Patent 2,300,749. The remixing step, after removal of part of the saponifying reagent from the mixer and before centrifugation, may also sometimes beomitted. Many other possibilities for modification fall within the scope of the invention, and I do not therefore wish to be limited except by the scope of the following claim.

I claim:

In the manufacture of soap, the process comprising continuously converting fat into soap by mixing said fat vigorously with a saponiiying reagent at a saponifying temperature during passage through a mixing zone, graining the soap resulting from said mixing step, thereafter pass- 6 ing the resulting mixture 0! grained soap and aqueous phase through an aging zone in which the mixture is churned by agitation of a degree less than that maintained in the preceding mixing zone, removing a part of the aqueous phase by gravity settling through said aging zone, passaqueous phase.

LEOPOLD SENDER. 

